Official opening of the post office was August 27, 1946. The name on the registration label was initially spelled SOHANA, later changed to SOHANO as of October 1948.
On March 28, 1949 the post office at SOHANO was renamed. The new date stamp was wrongly inscribed with the name ending with an "A". During this time the usual handwritten registration labels also carried the misspelled name. Corrected registration labels are known after June 1949.
Only after May 4, 1955 do we see a unified approach were date stamp matched the inscription on the registration label.